Most students believe that repeatedly reviewing course material is an effective study method, and surveys indicate that rereading textbook chapters is students’ most common study strategy (Amlund, Kardash, & Kulhavy, 1986; Karpicke, Butler, & Roediger, 2009). In one study, approximately two-thirds of students reported rereading text chapters in preparation for exams (Carrier, 2003). Repetition certainly can enhance memory. Surely everyone has experience with repeating a phone number or items from a shopping list in an effort to retain the information and perhaps transfer it to long-term memory. Not surprisingly, numerous studies demonstrate that memory is often enhanced when learners are exposed to information more than once (e.g., Rothkopf, 1968). However, most studies of this sort have been conducted in laboratory settings with immediate performance on a simple recall task as the criterion for successful learning. Research using learning content and assessments more directly relevant to education suggests that the benefits of repeated exposure to the same information – usually through rereading text materials – tend to be quite modest. Although students who report using more active study strategies that promote deeper processing and better retention tend to perform better on exams than students who simply reread text material, most students do not use these active strategies (Carrier, 2003).
Researchers have demonstrated that repeated exposure to academic material enhances learning at least somewhat beyond what can be acquired through a single reading. This unsurprising finding has been demonstrated in a variety of laboratory studies. For example, Amlund and colleagues (1986) randomly assigned graduate students to read a text passage either once, twice, or three times. Participants who read the passage more than once did so in immediate succession. Next, the students took a free recall test where they reproduced all the text they could remember from the passage, and a cued test made up of completion items. Participants who read the passage more than once recalled a significantly greater number of words and correctly answered more of the test items than students who read the passage only a single time. This difference in learning was only partially retained when participants were retested a week later. Importantly, there was no difference in immediate test performance between students who read the material twice and those who read it three times. The authors therefore concluded that the benefits of repeated exposure to text information are greatest the first time the content is reread. Subsequent readings appear unlikely to offer much additional benefit.
Several characteristics of Amlund and colleagues’ (1986) study may limit the generalizability of the findings to real-life academic settings. First, the roughly 700-word text passage that students read is much shorter than the text segments students typically read for their classes. Second, most students studying for actual classes probably do not reread the exact same text content immediately after reading it the first time. Finally, the differences between the single-read and multiple-read groups were significant when testing was immediate, but the benefits of rereading were small and were only partially retained on a delayed test. Given that there is generally some delay between when students do the bulk of their studying and when they take an exam, the benefits of rereading in preparation for a delayed test are more relevant to what happens in educational environments. Amlund and colleagues’ findings suggest that students gain little in terms of delayed test performance from reading text multiple times.
Researchers have also compared the effects of rereading content immediately versus having a delay between readings. Dunlosky and Rawson (2005) had undergraduate students read six passages adapted from a Graduate Record Examination (GRE) practice test. Students were randomly assigned to read the passages a single time, to reread them immediately, or to reread them a week after the first reading. Students then answered multiple-choice questions assessing knowledge of specific factual information from each passage, as well as questions requiring them to make inferences based on the passage content. Dunlosky and Rawson reported that rereading – whether immediate or delayed – had no effect on students’ test performance overall, nor did it improve performance specifically on either type of test question. Testing in this study was again conducted immediately after participants studied the text material. Researchers have extended such work by examining the effects of repetition on delayed test performance, which more closely mimics students’ real-life study activities.
Rawson and Kintsch (2005) compared the effects of immediate and delayed rereading on both immediate and delayed tests. They conducted two experiments with a total of more than 400 undergraduate participants, again randomly assigned to read text material a single time, to reread immediately, or to reread a week after the first reading. Half of the students were tested on the material immediately after their final reading of the text, and half were tested two days after their final reading. The test included a free recall task where participants reproduced all the content they could remember from one section of the text, as well as short-answer questions testing comprehension of text material. Immediate rereading led to better performance on an immediate test, but did not improve performance on a delayed test. In contrast, spaced rereading improved performance on a delayed test, but not on an immediate test. The authors concluded that distributed repetition led to more durable learning, and that learning associated with immediate repetition was far more fragile.
In a particularly thought-provoking study, researchers investigated whether the benefits of rereading might depend on students’ academic ability and the nature of the outcome measures used to assess learning. Barnett and Seefeldt (1989) used a median split of ACT scores to divide college students into groups of high and low academic ability. All students were randomly assigned to read, either once or twice, a passage on various legal principles. Students then took an essay test assessing knowledge of factual information taken directly from the passage, and also assessing their ability to apply what they had read to novel examples. The tests were scored by experimenters unaware of which students were in which experimental condition. When tested on direct factual information, high-ability students performed better than low-ability students, and those who read the passage twice performed better than those who read the passage once. More interestingly, when assessed on ability to apply what they had read, only high-ability students benefitted from reading the material a second time. Barnett and Seefeldt offered several possible explanations for this difference. They speculated that low-ability students may tend to emphasize concrete learning as they study or may put forth less effort when rereading because they have less insight into the shortcomings in their knowledge; alternatively, the study strategies used by high-ability students when rereading may be more sophisticated than those used by low-ability students. The researchers concluded that rereading can be an effective study strategy, but that students do not all benefit to the same degree and the benefits may not extend to all types of tests. Barnett and Seefeldt interpreted their findings in reference to students who complain that they read assigned material numerous times but still struggle on tests, emphasizing that when tests assess something beyond factual content, rereading is unlikely to offer much advantage – particularly for low ability students.
Several researchers have voiced concern that most studies of the effects of rereading have been conducted in laboratories rather than classrooms (e.g., Callender & McDaniel, 2009). Although laboratory research offers greater experimental control, the findings may have limited applicability to real-life educational practices. Callender and McDaniel attempted to bridge this gap by conducting four laboratory experiments using text content and test formats similar to those found in actual courses. In each experiment, undergraduate students were randomly assigned to either single or repeated reading groups. The text material was drawn from psychology textbooks and an article from a scholarly periodical appropriate for undergraduates, and the passages were longer (about 2,000 words) than those used in many laboratory studies. The effectiveness of rereading was assessed using multiple-choice and short-answer items focused on understanding of content rather than simple free recall of words.
Callender and McDaniel (2009) drew a number of important conclusions from their four experiments. Failing to replicate some earlier findings described above, the researchers found that rereading text did not improve learning regardless of whether students took a test of the material immediately or after a 24-hour delay. This was true regardless of participants’ reading comprehension ability and prior familiarity with the material – students with strong reading comprehension skills did not benefit from rereading more than students with poorer comprehension skills, nor did students studying content about which they had some prior knowledge benefit more than students studying unfamiliar material. Callender and McDaniel concluded that, in general, test performance is the same whether the content is read once or twice, and asserted that improvements in learning associated with rereading do not translate to real-life educational practices.
Other researchers have drawn similar conclusions to those reached by Callender and McDaniel (2009). Dunlosky, Rawson, Marsh, Nathan, and Willingham (2013) conducted a comprehensive review of research on the effectiveness of numerous study strategies. They confirmed that rereading is one of the most common study techniques used by students across all levels of academic performance. They also reported that repetition does tend to have some positive effect on learning and that this effect occurs whether participants read text passages or listen to the passages on an audio recording. Consistent with research cited early in this chapter, they concluded that rereading tends to be more beneficial when there are time lags between repetitions than when participants reread content immediately, and that most of the benefits of rereading occur after just one repetition – with additional repetitions providing little additional benefit.
Notwithstanding some limited potential increase in learning as a result of rereading, Dunlosky and colleagues (2013) also identified several important caveats. They note, for example, that all the experimental research on the effects of rereading academic material has taken place in laboratory settings rather than classrooms. No published experiments have included actual course content in an actual course setting, nor have any experiments included real class exams as outcome measures. This is particularly important given that researchers have observed little or no benefit from rereading when experimental materials closely resemble text content and assessment measures found in educational settings (see Callender & McDaniel, 2009). Dunlosky and colleagues further note that in most studies, participants reread content immediately and were then tested immediately, which does not necessarily mimic the way students actually study and take exams – a concern echoed elsewhere (Rawson & Kintsch, 2005). When participants are tested after a delay, those who had reread the material often do no better than those who had read it only once. Finally, any potential gains from rereading likely depend in part on the nature of the outcome measure. Dunlosky and colleagues point out that in studies using free recall tests, where participants must simply reproduce as much text as possible from memory, repeated reading tends to produce positive effects. However, students generally do not encounter such tests in academic settings. The researchers explain that some studies have shown positive rereading effects on measures such as completion tests of factual information, but benefits on multiple-choice tests are generally weak or nonexistent. For tests requiring participants to apply what they have read, rereading has again produced mixed results, with some studies showing modest benefits, some studies showing no benefits, and some studies showing benefits only for students with high academic ability. Given the equivocal findings across hundreds of studies, and the fact that rereading effects, when observed, tend to be small, Dunlosky and colleagues concluded that rereading has “low utility” (p. 29) as a study technique.
Given that repeatedly rereading academic material appears to produce limited gains in terms of student learning, it is important to consider whether students’ time would be better spent applying alternative study strategies. Alternative strategies would still require that students read information at least once, but might yield greater benefits than rereading because they require students to engage with the material in a more cognitively active manner. Students reading a text more than once may perform better on an exam than students who read only once and who do nothing else to prepare for the exam. Moreover, rereading content may be similarly effective to other relatively passive study techniques such as highlighting or summarizing (Rawson and Kintsch, 2005). However, in direct comparison with rereading, some techniques have proven to be far superior in terms of students’ test performance. The most noteworthy of these techniques is practice testing. Although there are other strategies that are also more effective than rereading, practice testing is unique in that students can apply the technique with very little training.
The testing effect, also known as test-enhanced learning, is addressed in Chapter 12, below, on multiple-choice testing, but is also relevant to the topic of studying by repetition. Research on the testing effect originated decades ago, but has expanded tremendously in recent years. The testing effect refers to the fact that taking a test tends to improve performance on subsequent tests of similar content, and tends to produce greater benefits than would occur from simply restudying the content (Roediger & Karpicke, 2006a). In a particularly vivid illustration of test-enhanced learning, Roediger and Karpicke (2006b) conducted two experiments involving academic text material. In the first experiment, undergraduate students read two brief text passages and then either read the text again or took a free recall test where they recalled as much of the text as possible from memory. All participants then took a recall test five minutes, two days, or one week later. When tested after only five minutes, students who reread performed better on a recall test than students who had taken a practice recall test. However, when tested after either two days or one week – a scenario more closely resembling what happens in real life – students who had taken a practice test performed better than students who had reread the text. That is, students who had taken a practice test rather than rereading retained more of the text material over time.
In their second experiment, Roediger and Karpicke (2006b) used an even more sophisticated research design. They assigned undergraduate students to one of three conditions in which some students read passages four times, some read three times and then took a free recall practice test, and some read only once and took three practice recall tests. Students then took a final recall test either five minutes or one week later. Replicating the pattern from the first experiment, students who read multiple times performed better on the immediate recall test than students in either of the practice test conditions. When tested after a week’s delay, however, students who had taken three practice tests recalled more information than students tested only once, and students tested once recalled more than students who simply reread the passages. Once again, taking a practice test led to better retention than simply rereading, and taking multiple practice tests led to better retention than taking a single practice test. What makes the findings even more striking is that Roediger and Karpicke used five-minute reading sessions and students were instructed to read the passage as many times as they could in that time frame. Students kept a tally of the number of times they had read the passage. Over the four sessions, students in the rereading condition read the passage an average of 14.2 times, whereas those in the repeated testing condition read it an average of only 3.4 times. Nonetheless, students in the testing condition retained a great deal more information a week later despite having received no feedback on their practice test performance.
In another recent study of test-enhanced learning, Weinstein, McDermott, and Roediger (2010) investigated whether students would benefit more by producing their own practice test questions than from taking an existing practice test. The researchers conducted three experiments in which students read three academic passages and then either reread them, produced their own practice test questions and answers based on the text, or took a practice test provided by the researchers. Students then took a final test on the content either immediately or after a two-day delay. The final test included both free recall and short-answer sections. Weinstein and colleagues reported that rereading led to poorer performance than either generating or responding to practice test items, and that this pattern occurred on both the immediate and delayed tests. The researchers also noted that students who responded to existing practice test items did as well on the outcome tests as students who generated their own practice items. Since generating one’s own items is more time-consuming than using existing items, the researchers suggest that students can use this strategy when practice tests are unavailable, but will benefit just as much from the more efficient technique of using existing practice tests when possible.
A variety of other studies substantiate the advantages of practice testing over repeatedly studying content, and demonstrate that these advantages are neither short-lived nor limited to material explicitly appearing on the practice tests. For example, Larsen, Butler, and Roediger (2009) found that the benefits of practice testing relative to simple restudying were still present on a test given after a six-month delay. There is also evidence that practice testing leads to deeper and more meaningful cognitive processing of material, as evidenced by the fact that practice testing improves learning of related but untested content (McDaniel, Thomas, Agarwal, McDermott, & Roediger, 2013). The testing effect even translates to learning classroom lecture content. Students who took a short-answer test after viewing a lecture tended to retain more information than students who restudied a summary of the lecture (Butler and Roediger, 2007).
A thorough review of the research on the benefits of practice testing is beyond the scope of this chapter, but interested readers are encouraged to examine comprehensive reviews available elsewhere (Roediger & Karpicke, 2006a; Roediger, Agarwal, Kang, & Marsh, 2010; Dunlosky et al., 2013). Dunlosky and colleagues noted that research demonstrating the benefits of practice testing goes back more than a century, but given the sheer volume of recent research they focused mainly on the more than 100 studies conducted just in the ten years preceding their review. They drew several conclusions from the existing literature. First, practice testing using a variety of test formats – including free recall, short-answer, completion, and multiple-choice – can enhance performance on later tests. Free-recall and short-answer tests generally produce greater retention benefits than other formats – probably because they require students to engage in the more effortful retrieval process of producing answers rather than recognizing them. Nonetheless, practice testing is generally more beneficial than rereading regardless of the practice test format. Second, practice testing likewise produces benefits on a variety of outcome test formats, including those most commonly used in education (short-answer, completion, and multiple-choice). Third, practice testing can improve learning even when the final test is of a different format than the practice test, when the material on the final test is related but not identical to the material on the practice test, and when the tests involved go beyond content knowledge to include comprehension and application of learned material. Finally, the benefits of practice testing are evident in studies across a wide range of participant ages, educational levels, and ability levels, and the effects appear to be quite durable – having been demonstrated after as long as several years following initial study. Dunlosky and colleagues’ overall assessment is that as a study strategy, practice testing has “high utility” (p. 35).
It is important to note that practice testing is not the only study strategy that generally produces greater learning benefits than rereading. Roediger and Pyc (2012) identify two other active study strategies that tend to provide advantages over restudying content. When using the technique known as elaborative interrogation, students actively produce their own explanations for the claims they have read about. A related technique known as self-explanation is a metacognitive strategy whereby students monitor and actively explain their learning as they read. The limitation of these strategies is that they require more time than either rereading material or taking a practice test, which might limit their practicality – particularly with less motivated students.
Students often have limited awareness of the relative effectiveness of various study techniques, and most students report that no one has ever taught them how to study (Kornell & Bjork, 2007). Karpicke and colleagues (2009) surveyed undergraduate students from a highly competitive university about the strategies they use to prepare for exams. Repeatedly rereading text material was by far the most commonly reported strategy, and more than half of the students reported it as their primary strategy. Only a small minority of students reported using strategies that involve active memory retrieval, and only 1% reported that such a strategy was their primary study technique. Interestingly, using practice testing as a deliberate study strategy is positively associated with grade point average (Hartwig & Dunlosky, 2012). Fewer than one in five of the students in Karpicke and colleagues’ study reported that they would use practice testing rather than some other method such as rereading, and most of these students indicated that they would use practice tests to identify what they still needed to study rather than to enhance their learning. Karpicke and colleagues concur with other researchers (e.g., Fritz, Morris, Bjork, Gelman, & Wickens, 2000; Wiley, Griffin, & Thiede, 2005) that repeated exposure to text content tends to make students feel more familiar with the material without necessarily increasing their knowledge or comprehension of the content. Accordingly, Roediger and Karpicke (2006b) found that students who read text content repeatedly without practice testing were more confident than students who took practice tests about how much information they would remember a week later – confidence that subsequent tests of the material revealed to be unfounded.
Roediger and Pyc (2012) assert that students should be taught about the effectiveness of active study techniques that are likely to produce much greater benefits than rereading course material. Practice testing is likely to be particularly advantageous because it does not require a great deal of special instruction and is generally no more time consuming than rereading. Of course, the effectiveness of any study technique depends on student motivation. Rereading, practice testing, and all other study strategies are irrelevant for students who do not study the first time, but motivated students will likely learn more effectively by applying alternatives to rereading.